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			<h1>common_schema</h1> <strong>2.2</strong> documentation
			<div class="subtitle">DBA's framework for MySQL</div>
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				<h2><a href="innodb_index_stats.html">innodb_index_stats</a></h2>	
<h3>NAME</h3>
innodb_index_stats: Estimated InnoDB depth & split factor of key's B+ Tree  
<h3>TYPE</h3>
View

<h3>DESCRIPTION</h3>

<p><i>innodb_index_stats</i> extends the <a href="http://www.percona.com/docs/wiki/percona-server:features:innodb_stats#innodb_index_stats">INNODB_INDEX_STATS</a> patch
in Percona Server, and presents with estimated depth & split factor of InnoDB keys.
</p>

<p>
Estimations are optimistic, in that they assume condensed trees. 
It is possible that the depth is larger than estimated, and that split factor is lower than estimated.
</p>

<p>Estimated values are presented as floating point values, although in reality these are
integer types. 
</p>

<p>This view is experimental and in BETA stage. 
</p>

<p>This view depends upon the <a href="http://www.percona.com/docs/wiki/percona-server:features:innodb_stats#innodb_index_stats">INNODB_INDEX_STATS</a> patch
in Percona Server.  
</p>

<p>
Note that Percona Server 5.5.8-20.0 version introduced changes to the INNODB_INDEX_STATS schema.
This view is compatible with the new schema, and is incompatible with older releases.
</p>

<h3>STRUCTURE</h3>

<blockquote><pre>
mysql&gt; DESC common_schema.innodb_index_stats;
+--------------+---------------------+------+-----+---------+-------+
| Field        | Type                | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+-------+
| table_schema | varchar(192)        | NO   |     |         |       |
| table_name   | varchar(192)        | NO   |     |         |       |
| index_name   | varchar(192)        | NO   |     |         |       |
| fields       | bigint(21) unsigned | NO   |     | 0       |       |
| row_per_keys | varchar(256)        | NO   |     |         |       |
| index_size   | bigint(21) unsigned | NO   |     | 0       |       |
| leaf_pages   | bigint(21) unsigned | NO   |     | 0       |       |
| split_factor | decimal(23,1)       | NO   |     | 0.0     |       |
| index_depth  | double(18,1)        | NO   |     | 0.0     |       |
+--------------+---------------------+------+-----+---------+-------+
</pre></blockquote>

<h3>SYNOPSIS</h3>

<p>Columns of this view map directly to those of 
<a href="http://www.percona.com/docs/wiki/percona-server:features:innodb_stats#innodb_index_stats">INNODB_INDEX_STATS</a>, 
with the addition of:</p>
<ul>
	<li><strong>split_factor</strong>: Estimated split factor of the index tree</li>
	<li><strong>index_depth</strong>: Estimated depth of the index tree. Value is a floating point, though the depth of an index is an integer.</li>
</ul>

<h3>EXAMPLES</h3>
<p>Examine index attributes on a specific table:</p>
<blockquote><pre>mysql&gt; SELECT * FROM common_schema.innodb_index_stats WHERE TABLE_NAME='docs_template';
+--------------+---------------+-----------------+--------+--------------------------+------------+------------+--------------+-------------+
| table_schema | table_name    | index_name      | fields | row_per_keys             | index_size | leaf_pages | split_factor | index_depth |
+--------------+---------------+-----------------+--------+--------------------------+------------+------------+--------------+-------------+
| databus      | docs_template | unique_docs_idx |      4 | 28697340, 28697340, 1, 1 |     834310 |     725102 |          7.6 |         7.6 |
| databus      | docs_template | PRIMARY         |      1 | 1                        |   18851201 |   16485198 |          8.0 |         9.0 |
| databus      | docs_template | doc_timestamp   |      2 | 12, 1                    |     127577 |     126428 |        111.0 |         3.5 |
+--------------+---------------+-----------------+--------+--------------------------+------------+------------+--------------+-------------+
</pre></blockquote>

<h3>ENVIRONMENT</h3>
Percona Server &gt;= 5.5.8-20.0 with <a href="http://www.percona.com/docs/wiki/percona-server:features:innodb_stats#innodb_index_stats">INNODB_INDEX_STATS patch</a>

<h3>SEE ALSO</h3>
<a href="innodb_index_rows.html">innodb_index_rows</a>

<h3>AUTHOR</h3>
Shlomi Noach
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